GTi Oil Leak

2001 GTi that when it sits for awhile there is oil in the bilge. I have tried to look all over and can't see where the leak is coming from. The tank is dry. Off the bottom of the tank are 2 lines - one maybe 1/4" and the other larger ?3/8" running to under the carb. and another large line off the top ?3/8" tounder the exhaust.
What are each of these lines?
It almost drained the tank epmty while sitting in storage.
Any ideas? Thanks

You can always clamp off the Oil line and remove the tank, then connect a LOW Pressure *HAND* Pump (Pop-Off Pump) to the check valve which comes off the top fitting. That check valve lets air *in* as the Oil level drops.

Pressurize to *NO MORE* than 3psi and spray soapy water around the lower and upper grommet seals and around the edges of the tank. If your leak is coming from the tank or fittings, you'll find it......

To seal off the large Oil Tubing fill opening, use a couple baggies stacked on top of each other and the OE screw clamp, or a big rubber stopper.

Another possible leak spot are the small Injection Oil Lines (2).
Remove the Carb. Air Box (big black plastic piece) above the Carb. and carefully check and flex those small Oil lines. If they are cracked or feel stiff, replace them before they fail altogether and take out your engine for lack of lubrication.